THE EARTHQUAKE ADVANCE THEORY 193
in Alaska, besides those in Yakutat Bay.1 For example, Muir Glacier advanced about 300 yards between 1890 and 1892; Patterson Glacier was advancing and destroying trees in 1891; Taku Glacier had a slight net advance between 1890 and 1905; Brady Glacier advanced 5 miles between 1794 and 1894, the destruction of trees being in progress in 1880; LaPerouse Glacier was advancing and destroying forest in 1895, but ceased before 1899, readvancing into the forest once more between 1909 and 1910; two of the Lituya Bay glaciers advanced two and a half and three miles respectively between 1786 and 1894, one advancing another half mile between 1894 and 1906; the Alsek river terminus of the Grand Pacific through-glacier was advancing and destroying forest in 1908; another glacier coming into the Alsek valley from the west, and connected with the Hidden-Nunatak-Yakutat glacier system, though inactive in 1906 and 1908, possibly advanced in 1909; a small glacier opposite the Frederika Glacier in the Wrangell Mountains was advancing in 1908; Childs Glacier advanced in 1910; Logan Glacier, north of Mt. St. Elias, advanced in 1918, after at least £00 years of inactivity; Rainy Hollow Glacier advanced 2000 feet in 3 months in 1910; Rendu Glacier in Glacier Bay advanced l£ miles between 1907 and 1911; an adjacent cascading glacier advanced J mile in 1911; Grand Pacific Glacier advanced about 4000 feet between August, 1912, and September, 1913, and three other ice tongues in Glacier Bay were moving forward in 1913. In these and many other parts of Alaska some glaciers have, in general, been retreating steadily within historic times.
Our own view would now be that any or all of the advances of Alaskan glaciers cited might be due to earthquake avalanching rather than climatic variations, the earthquake data being no more incomplete than the climatic data. Indeed, in view of the Yakutat Bay cases, the greater advances, such as the 20 mile advance of Malaspina Glacier described in Chapter HE, the 5 mile movement of Brady Glacier and the 2 to 3 mile advances of the Lituya Bay glaciers, are far more suggestive of spasmodic earthquake advances than of climatic variation, and some of the smaller ones may be due to earthquakes and some to climatic oscillations. These glaciated mountains are known to be frequently shaken by severe earthquakes.2
If avalanching during the 1899 earthquakes of Yakutat Bay caused the advance of the glaciers there during the ensuing ten or more years, then it ought to be carefully considered whether similar avalanching in the snow-laden Fairweather Range might not have caused the 2 and 3 mile advances of the Lituya Bay glaciers between 1786 and 1894 as a result of the earthquakes felt at Sitka in either 1843, 1847, 1861, or 1880; whether the same earthquake did not cause avalanching which resulted in the 5 mile advance of Brady Glacier between 1794 and 1894; and whether the earthquake of 1900 in the Chugach Mountains did not similarly cause the slight advances of Valdez, Shoup, Columbia and adjacent glaciers, as some earlier earthquake may have caused the 1892 advance of Columbia Glacier, the 1890-92 advance of Muir Glacier, and the others cited. Many of the minor oscillations like the last mentioned might be climatic, though that leaves their localization unexplained. It is just as logical to assume that they were not climatic, since the earthquake explanation does account for the localization, as it is to assign to them a climatic cause.
i For a more complete list of such advances, see Martin, Lawrence, Guidebook No. 10, Excursion C 8, International Geological Congress, Ottawa, 1913, pp. 157-162.
> Martin, Lawrence, The Alaskan Earthquakes of 1899, Bull. Geol. Soc. Amer., Vol. XXI, 1910, pp. 339-400; Tarr, R. S. and Martin, Lawrence, Professional Paper 69, U. S. Geol. Survey, 1912. 13